JP2001232792A - Liquid transporter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid transporter for transporting liquid in one direction through volumetric variation of a cavity section provided in a liquid channel in which efficiency of liquid transportation is enhanced by preventing backflow of liquid and adhesion of bubbles to the liquid channel in order to enable and facilitate manufacture through micromachining, etc. SOLUTION: Resistance imparting parts having no movable part in a liquid channel at least on the upstream side or downstream side of a cavity section are provided while arranging the liquid transporting direction to the direction of increasing conductance and subjected to hydrophilic treatment in the vicinity of the inner wall face thereof. In place of hydrophilic treatment, the inner wall face of the resistance imparting part may be curved smoothly and continuously in the liquid transporting direction. A relation 0<β<α may be set between the angle β of an inclining face rising from the upstream side toward the throat of the resistance imparting part where the area of the liquid channel is minimum and the angle αof an inclining face rising from the downstream side toward the throat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid transport apparatus for transporting a liquid in a fixed direction by using a resistance applying portion whose conductance changes depending on the flow direction of the liquid.

[0002]

2. Description of the Related Art Various types of image recording heads for forming an image by controlling the amount of ink ejection based on an image signal have been proposed. For example, an image forming apparatus that forms an image by changing the density of ejected ink is known (U.S. Pat. Nos. 4,109,282 and 4,61).
No. 4,953, JP-A-5-201024, 7-125
259, 3-207664, and 9-156131).

[0003] US Patent No. 4,109,282 (hereinafter referred to as prior art document 1) discloses a flap valve and a flap valve in a flow path for guiding two liquids of a clear ink and a black ink to a substrate for image formation. There is disclosed a printing apparatus in which a valve is provided, the valve is displaced to open and close the flow path of each ink, and two liquids are mixed to a desired concentration and transferred onto a substrate. Thus, an image having the same gray scale information as the image information displayed on the TV screen can be printed out. Here, it is disclosed that a voltage is applied between a valve of a flap valve and an electrode provided on an opposite surface thereof, and the valve is displaced by mechanically deforming the valve itself by the electrostatic attraction. I have.
The ink is sucked out by the capillary action between the fibers of the printing paper.

[0004] US Pat. No. 4,614,953 (hereinafter referred to as Prior Art Document 2) discloses a printer head device in which a plurality of inks and solvents of the same color are introduced into a third chamber in desired amounts and mixed. Have been. Here, as means for weighing a desired amount of ink, a chamber,
It is disclosed that a diaphragm-shaped piezo effect element unit attached to the chamber is used, and a pressure pulse obtained by driving the piezo element is used.

Japanese Patent Application Laid-Open No. 5-201024 (hereinafter referred to as Prior Art Document 3) discloses a liquid chamber filled with a carrier liquid, an ink jet driving means provided in the liquid chamber, and a nozzle communicating with the liquid chamber. And a mixing unit for mixing the ink with the carrier liquid in the nozzle. It also discloses that an adjusting means utilizing an electroosmosis phenomenon is provided to adjust the mixing amount of the ink to a desired value.

Japanese Patent Application Laid-Open No. 7-125259 (hereinafter referred to as Prior Art Document 4) similarly discloses first and second supply means for supplying inks having first and second densities, and a desired ink density. Thus, an ink jet recording head having a control means for controlling the supply amount of the second ink by the second supply means is disclosed.

Here, as a control means, a means using a micropump having a dedicated heating element and driven by the heat energy is disclosed. As the micropump, there is disclosed an example in which heat energy is generated by a heat generating element, and a piston-like valve or a cantilever-like valve is driven by pressure generated by nucleate boiling. It is also described herein that the use of the valve in combination with an actuator made of a shape memory alloy makes it possible to effectively control the amount of ink inflow particularly in a region where the amount of inflow is small.

Japanese Patent Laid-Open No. 3-207664 (hereinafter referred to as Prior Art Document 5) has a structure similar to that of Prior Art Document 2, but controls the ejection amount of a plurality of inks by a pulse width applied to a piezoelectric element. A structure in which these are mixed is shown.

Japanese Patent Application Laid-Open No. Hei 9-156131 (hereinafter referred to as prior art document 6) includes a plurality of printer heads for forming images of a plurality of colors based on image data, and mixes ink and diluent at a predetermined mixing ratio. An ink jet printer is shown in which a diluted ink is mixed to form a diluted ink, and the diluted ink is ejected from a nozzle to form a recorded image on a recording medium. Here, when, for example, all-white image data in which the amount of mixed ink is small and does not reach a clear print density is input to the plurality of printer heads, the diluting liquid is supplied from at least one of the plurality of printer heads. There is disclosed an ink jet printer for discharging ink. As a result, a rapid change in gradation (tone jump) is prevented, and unnecessary consumption of the diluent is suppressed, and the drying property is improved. The volume of the diluent is controlled by a pulse voltage, a pulse width, the number of pulses, and the like applied to a driving unit formed of a piezoelectric element.

As described above, in the prior art document 1, the amount of ink flowing down by gravity is controlled by changing the opening area of the ink discharge port. In Document 2, the amount of ink ejection is controlled by the amount of displacement of the diaphragm and the number of times of displacement. In Literature 3, the discharge amount of ink is controlled by electroosmosis.
In Document 4, the amount of ink discharged beforehand is controlled by a micropump that is opened and closed by a heater. Reference 5
Is controlled by the amount of displacement and the number of times of displacement of the piezoelectric element. In Document 6, the ink ejection amount is controlled by displacing the wall of the ink tank by a piezoelectric element.

[0011]

Among these prior arts, those having a pump function for positively discharging ink include those described in References 2, 5, and 6. However, each of these has a pressurized chamber (cavity portion) having an enlarged volume in the middle of the ink flow path, and the volume of the pressurized chamber is changed by vibration of a diaphragm or a tank wall. The upstream side and the downstream side do not have a check valve for preventing the backflow of ink. For this reason, there is a problem that the ink flows backward to the upstream side along with the change in the volume of the pressurizing chamber, and the reverse flow rate increases, thereby deteriorating the efficiency of the pump.

[0012] Therefore, the applicant has applied a pressure chamber (cavity).
It is being considered to provide a resistance applying portion (throttle) whose conductance (reciprocal of resistance) changes depending on the flow direction of the ink on the upstream side (inlet side) and downstream side (outlet side) of Japanese Patent Application Laid-Open No. Hei 11 (1999) -107. No. 351008). Since this resistance imparting portion does not have a mechanically movable part such as a general one-way valve, it has excellent durability and reliability, and can be manufactured by a manufacturing method such as a micromachine, and is easy to manufacture. Has the advantage that

However, since the resistance imparting portion has a geometrically complicated portion such as a small restrictor on the inner wall surface of the flow path, if the liquid contains fine bubbles, the bubbles may become complicated. It is easy to be captured and adhered to the shape part. It is extremely difficult to discharge these air bubbles when they enter fine grooves or the like in the resistance applying section.

If the air bubbles adhere in this manner, the volume of the air bubbles changes with the change in the volume of the cavity, and the driving energy for changing the volume of the cavity cannot be sufficiently transmitted to the liquid. It is conceivable that the pump efficiency will deteriorate.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and prevents a backflow of a liquid such as ink, and prevents bubbles from adhering to a liquid flow path to efficiently transport a liquid in one direction. It is another object of the present invention to provide a liquid transport apparatus that can be manufactured using a manufacturing method such as a micromachine and can be easily manufactured.

[0016]

According to the present invention, an object of the present invention is to provide a liquid transport apparatus for transporting a liquid in one direction by changing the volume of a cavity provided in a liquid flow path. And a resistance imparting portion having no movable portion on at least one of the downstream side is provided so that the direction in which the conductance increases is aligned with the liquid transport direction, and hydrophilic treatment is performed near the inner wall surface of the resistance imparting portion. This is achieved by a liquid transport apparatus characterized in that:

The same object is to provide a liquid transport apparatus for transporting a liquid in one direction by changing the volume of a cavity provided in a liquid flow path, wherein at least one of an upstream side and a downstream side of the cavity is provided in the liquid flow path. The resistance imparting portion having no movable portion is provided so that the direction in which the conductance increases is aligned with the liquid transport direction, and the inner wall surface of the resistance imparting portion is formed of a curved surface that smoothly continues in the liquid transport direction. It is also achieved by a liquid transport device characterized by the above.

The same object is to provide a liquid transport apparatus for transporting a liquid in one direction by changing the volume of a cavity provided in a liquid flow path, wherein at least one of an upstream side and a downstream side of the cavity is provided in the liquid flow path. A resistance applying portion having no movable portion is provided so that the direction in which the conductance increases is aligned with the direction of liquid transport, and the resistance applying portion rises from the upstream side toward the throat where the liquid flow path cross-sectional area is minimized. A liquid transport device, wherein a rising angle β of the slope and a rising angle α of the slope rising from the downstream side toward the throat are set to satisfy 0 <β <α,
Is also achieved by

Such a structure for preventing the adhesion of air bubbles may be provided in all the resistance applying portions. However, only some of the resistance applying portions have the structure for preventing the air bubble adhesion. There may be.

In order to change the volume of the cavity, a structure in which a movable wall driven by a drive unit is provided in the cavity and the movable wall is moved can be used.
For example, it is possible to form a part of the wall of the cavity portion with a diaphragm and drive the diaphragm using a piezo element (piezoelectric element), a magnetostrictive element, or an electrostatic force.

The resistance applying portion may have a geometrical shape in which the conductance in the liquid transport direction is larger than the conductance in the opposite direction. For example, it is possible to adopt a shape of a divergent nozzle in which the cross-sectional area rapidly increases on the upstream side and the cross-sectional area gradually increases on the downstream side across the throat where the cross-sectional area of the flow path is minimized. The resistance applying portion may be provided on both the upstream side and the downstream side of the cavity portion, or may be provided on only one of the upstream side and the downstream side. If a plurality of resistance applying portions are provided on at least one of the upstream side and the downstream side of the cavity portion, the function of preventing the liquid from flowing backward is further increased, and the transport efficiency can be further improved.

This liquid transport device can be used for an image recording head. That is, an image can be formed by controlling the ink ejection amount based on the image signal. In this case, it is preferable that the discharge amount of the ink is always substantially constant. For this purpose, the ink to be ejected is
An image non-forming liquid (transparent ink) that does not substantially form an image after drying and an image forming liquid (colored ink such as black ink) that substantially forms an image after drying are formed. What is necessary is just to control the discharge amount of each liquid so that the flow rate becomes substantially constant.

One color ink may be supplied to one ink discharge port from one ink channel. For example, when printing is performed in a single color by a print printer or the like, or when the color of each pixel is set by a combination of inks of different colors discharged from a plurality of ink discharge ports, such a method can be used. A plurality of ink channels of different colors are assembled on the upstream side of one ink ejection port, and the color of the fluid ejected from the ink ejection port is controlled by separately controlling the amount of ink supplied from each ink channel. You may make it set.

The ink is continuously ejected from the ink ejection port, and the ink can be transferred to the image receptor as a continuous fluid (continuous coating method). When the ink to be transferred from one ink discharge port to the image receptor is formed by the non-image forming liquid and the image forming liquid, the respective liquids may be mixed homogeneously. It may be applied in a state of being layered.

The ink ejected from the ink ejection port can be made to fly as an ink droplet to the image receptor (ink jet system). In this case, the ink can be ejected directly from the ink ejection port in an ink-jet state by the displacement of the movable member of the ink ejection pump.
However, the fluid whose flow rate is controlled by the displacement of the movable member may be guided to the image receptor by an ink jet method using a separately provided ink transfer means.

[0026]

FIG. 1 is a conceptual view of a continuous coating type image forming apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of an image recording head used here, and FIG. FIG. 4 is an enlarged cross-sectional view of the resistance applying section.
In FIG. 1, reference numeral 10 denotes a platen, and reference numeral 12 denotes a print sheet wound around the platen 10 as an image receptor. The printing paper 12 is fed at a constant speed in the direction of the arrow by the clockwise rotation of the platen 10 in the drawing.

Reference numeral 14 denotes an undercoating section, which applies a transparent undercoating liquid to the printing paper 12 in order to improve the adhesion of the ink and improve the image quality. An image recording head 16 forms an image on the print paper 12 by mixing the first ink and the second ink and guiding the mixture to the print paper 12. Reference numeral 18 denotes a heater for heating the print paper 12 on which an image is formed by the image recording head 16 and drying the ink.

The image recording head 16 is, as shown in FIG.
A first ink flow path 20 and a second ink flow path 22 are provided, and the first ink and the second ink are supplied to these flow paths 20 and 22, respectively. The flow rates of the respective inks are controlled by the ink discharge pumps 24 and 26 and then merged to be led to the ink discharge ports 28.

The ink discharge ports 28 are provided for each pixel in the width direction of the printing paper 12, and ink whose density and / or color is controlled corresponding to each pixel is discharged from each ink discharge port 28. As the first ink, a colorless and transparent ink, that is, an ink that becomes colorless and transparent when dried, can be used, and includes an anti-fading agent such as an antioxidant and an ultraviolet absorber. The second ink is, for example, black ink.

The first and second inks are stored in ink tanks 30 and 32, respectively, and are supplied from the ink tanks 30 and 32 by ink supply pumps 34 and 36, respectively. At a constant pressure. As the pumps 34 and 36 used here, for example, those having a pressure regulating valve on the ink ejection side and maintaining a constant ejection pressure are suitable. In addition, tank 30,
A type in which the ink is pressurized by supplying a constant air pressure to them as a sealed type is also suitable. The ink is stored in the ink tank 3 by capillary action of a thinner pipe.
It may be one that sucks up from 0,32.

The ink discharge pumps 24 and 26 are, for example, 1
One corresponding to one pixel can be formed on a common substrate. The image recording head 16 can be manufactured by stacking the substrates prepared for the respective pixels with the partition plate interposed therebetween.

The pumps 24 and 26 are provided with resistance applying portions 42a and 42b and 44a and 44b having no movable portion, and between the resistance applying portions 42a and 42b and 44a and 44b.
b, and the diaphragms 50 and 52 facing the cavities 46 and 48, respectively.
And drive units 54 and 56 for driving these diaphragms 50 and 52.

The resistance applying sections 42a, 42b and 44a,
Reference numeral 44b is a diaphragm having no movable portion and having a shape in which conductance (reciprocal of resistance) changes with respect to the cavities 46 and 48 depending on the direction of ink flow. That is, these resistance applying portions 42a, 42b, 44a, 44
b is a diaphragm having a geometric shape such that the conductance (reciprocal of resistance) in the ink flow direction (transport direction) is larger than the conductance in the opposite direction. Therefore, it has no movable parts and can be easily manufactured by a micromachine manufacturing method. Since these resistance applying portions 42a, 42b, 44a and 44b have the same structure, one of the ink discharge pumps 24
The structure will be described using one resistance applying portion 42a used in the first embodiment.

As shown in FIG. 3, the resistance applying section 42a is provided on the slope A where the area of the ink flow path increases almost continuously in the ink flow direction (the direction from left to right in FIGS. 2 and 3).
And a plane B in which the area of the ink flow path sharply increases in the opposite direction. In other words, the divergent nozzle is long on the downstream side and short on the upstream side, with the throat having the smallest flow path cross-sectional area.

The operation of the resistance applying section 42a will be described qualitatively. First, when the ink flows from the left side to the right side in FIGS. 2 and 3, the ink flows through the throat and along the slope A in a flow close to rectification. Therefore, the pressure loss at that time is small, and the flow resistance is small. Conversely, when the ink flows from the right side to the left side, the ink passes through the throat and expands more rapidly in the plane B, resulting in turbulence. For this reason, pressure loss increases and flow resistance increases. Note that the flow direction in which the flow resistance increases may be reversed depending on the angle between the planes A and B. In this case, the direction of the resistance applying section is reversed.

Between the resistance applying portions 42a and 42b and 44
a and 44b have a cavity portion 46 having a variable volume.
48, and the volumes of the cavities 46 and 48 are adjusted by diaphragms 50 and 52 driven by driving units 54 and 56, respectively.
Varies by. Piezoelectric elements (piezoelectric elements) and magnetostrictive elements are suitable for the driving units 54 and 56, and PZT (lead titanate.
Lead zirconate solid solution), barium titanate (BaTiO)
₃ ), a piezo element using a solid solution of PZT and barium titanate is most suitable.

The driving units 54 and 56 may use other effects instead of those using the piezo effect or the magnetostriction effect. Heat-pressure effect, electrostatic attraction or electrostatic repulsion, effect of interfacial tension of a fluid different from multiple fluids used for image formation, generated by electrolysis and / or heat of fluid different from multiple fluids used for image formation A bubble, an effect of changing the flow resistance of a fluid different from a plurality of fluids used for image formation to change the liquid pressure of the liquid, or the like may be used.

When the volumes of the cavities 46 and 48 fluctuate due to the fluctuations of the diaphragms 50 and 52, ink reciprocates in the resistance applying sections 42a and 42b and 44a and 44b. In this case, the resistance of the ink flowing toward the right in FIGS. 2 and 3 decreases, and the resistance increases when the ink flows in the opposite direction (left). For this reason, due to the continuous volume fluctuation of the cavities 46 and 48, the ink flows in the direction of low resistance, and functions as a check valve.

The resistance applying portions are the cavity portions 46 and 48.
If a plurality of pumps are provided on the upstream side and the downstream side, respectively, the function of the pump is improved, but one resistance applying section provided on one of the upstream side and the downstream side may be provided. If two or more cavities are provided on both sides of the cavities 46 and 48 as in this embodiment, the function of the pump is further improved.

When the driving units 54 and 56 are driven, the diaphragms 50 and 52 move into and out of the cavities 46 and 48, and the volumes of the cavities 46 and 48 change. Therefore, the ink flows toward the ink discharge port 28. If the movement range of the diaphragms 50 and 52 at this time is regulated to be constant, the amount of ink ejected by one reciprocating movement of the diaphragms 50 and 52 becomes constant. Therefore, each drive unit 54,
By controlling the number of drive pulses to be applied to 56, the supply amounts of the first and second inks can be controlled with high accuracy.

As described above, if the amount of ink discharged by one reciprocating movement of the driving units 54 and 56 is made constant, the amount of ink discharged by each of the ink discharge pumps 24 and 26 becomes equal to that of the driving units 54 and 56.
Is proportional to the number of times of driving. Here, the control unit 62 controls the total supply amount S ₀ of the first and second inks supplied from the respective ink passages 20 and 22 to be always constant.
(FIG. 1) controls the driving units 54 and 56.

The control unit 62 includes an arithmetic unit 64 and drivers 66 and 68 as shown in FIG. The operation unit 64
The mixing ratio (S ₁ / S ₂ ) of the first and second inks is calculated based on the density signal (image signal). Here, the supply amounts S ₁ and S ₂ of the first and second inks are the sum (S ₁ +
S ₂ ) is determined to be a fixed amount S ₀ . Driver 66,
Reference numeral 68 drives the driving units 54 and 56 such that the supply amounts of the flow paths 20 and 22 become S ₁ and S ₂ .

The driving units 54 and 56 are driven by pulses.
The number of pulses causes the diaphragms 50 and 52 to open.
The number of closings is controlled, and as a result, the flow rate S₁, S_TwoIs controlled
It can be configured as follows. In this case, the ink flow path
Flow resistance of 20, 22, ink supply pressure and diaphragm
50, 52 opening / closing conditions etc. are prepared, and one pulse
Therefore, the amount of ink ejected from each is the same
Then, the total number of driving pulses of the driving units 54 and 56 is constant.
By controlling the total flow rate S ₀= S₁+
S_TwoCan be managed constantly.

As described above, the image recording head 16 is formed by alternately stacking substrates and partition plates. Each board has
As shown in FIG. 2, ink ejection ports 2 corresponding to one pixel
8, ink flow paths 20, 22, ink discharge pumps 24, 2
6 are formed. Here, the ink discharge port 28 of each substrate is
The print papers 12 are arranged on a straight line perpendicular to the running direction.
Further, in this case, the interval between the adjacent ink ejection ports 28 matches the pixel interval of the recorded image. Therefore, one substrate and one
The total thickness of the partition plates corresponds to the pixel interval.

As described above, the ink discharge pumps 24, 2
The first and second inks whose flow rates were controlled in Step 6 are the first and second inks.
And the ink discharge port 2 where the second flow paths 20 and 22 merge
8 and is discharged as a continuous flow.
Is continuously applied to the printing paper 12 facing and opposed to the printing paper 12. At this time, the total discharge flow rate S ₁ + S ₂ =
Since S ₀ is controlled to be constant, the ink can be smoothly and stably applied to the print paper 12. In this case, the first and second inks are applied as a non-disturbed laminar flow without mixing with each other as shown in FIG.

Here, the laminar flow includes a mixed flow only near the boundary between the first and second inks. 1st, 2nd
May be mixed uniformly, but by forming a laminar flow in this way, the surface of the image formed on the print paper 12 can be covered with any of the inks (here, the first ink). In addition, the image quality can be improved by using any of the inks (here, the second ink) as inks that are familiar with the undercoat layer of the print paper 12.

A large number of the first and second ink flow paths 20, 22 and the ink discharge pumps 24, 26 are arranged in parallel in the width direction of the print paper 12 (direction perpendicular to the moving direction) and are provided for each pixel. An image can be formed by controlling the ink discharge pumps 24 and 26 corresponding to the pixels with respective density signals (image signals). In this case, the ink ejection ports 28 can be independently provided to face the print paper 12 for each pixel. In addition, these ink discharge ports 28 can be opened in slits communicating with the print paper 12 in the width direction, and the ink liquid can be transferred from the slits to the print paper 12 in a belt shape and applied.

The image recording head 16 thus configured
In some cases, the ink guided from the ink tanks 30 and 32 to the image recording head 16 may contain fine bubbles. When the bubbles enter the ink discharge pumps 24 and 26, they easily adhere to the inner wall surfaces of the ink flow paths 20 and 22. In particular, in the resistance applying portions 42a, 42b, 44a, and 44b, the shape of the inner wall surface changes in a complicated manner, and the ink flow path area changes abruptly, causing a disturbance in the ink flow. Bubbles are easy to adhere.

Therefore, in this embodiment, the resistance applying section 42
a, 42b, 44a, and 44b are subjected to hydrophilic treatment P. That is, a hydrophilic treatment was applied to the plane B, which is a portion where bubbles easily adhere. FIG. 4 shows a cross section of one resistance applying portion 42a, but the other resistance applying portions 42b, 44
a and 44b have exactly the same structure, and needless to say, they are similarly subjected to hydrophilic treatment.

Here, the hydrophilic treatment can be performed by forming a hydrophilic resin film on the contact surface of the ink. As such a hydrophilic resin, a nylon resin, a polyvinyl alcohol resin or the like is suitable. The hydrophilic treatment can also be performed by applying a surfactant. Instead of performing the hydrophilic treatment only on the plane B of the resistance applying part 42a,
It may be applied to the slope A or the entire inner wall surface of the resistance applying section 42a, or the ink flow path 20 including the resistance applying sections 42a and 42b.
May be subjected to a hydrophilic treatment on the entire inner wall surface.

According to this embodiment, bubbles mixed into the ink enter the ink flow paths 20, 22, and the resistance applying sections 42a,
Even after passing through 42b, 44a, and 44b, the hydrophilic treatment is applied to the plane B of these resistance imparting portions 42a, 42b, 44a, and 44b to which air bubbles are particularly likely to adhere. Is discharged. This makes it difficult for bubbles to remain particularly near the cavities 46 and 48, and does not cause a decrease in pump efficiency.

[0052]

FIG. 5 is an enlarged sectional view of a resistance applying portion according to another embodiment. The resistance applying portion 142 has an inner wall surface formed of a curved surface that is smoothly continuous in the ink transport direction. That is, a smooth curved surface is used so that the inner wall surface does not change its shape in a complicated manner. In other words, the radius of curvature of the inner surface does not change abruptly.

According to this embodiment, the ink flow path 120
Curved R1 can in the corner of the wall B rising from the inner wall surface of a smooth curved surface R ₂ next to the throat of the edge (plane B and slope A intersect portion) does not become edge-shaped, inclined surface A and the ink flow path 120
And the inner wall surface can curved surface R ₃ in the corner of intersection of. This makes it difficult for air bubbles to adhere to these corners and edges. Therefore, bubbles are less likely to remain in the cavity, and the pump efficiency is not reduced.

[0054]

FIG. 6 is an enlarged sectional view of a resistance applying portion according to another embodiment. The resistance imparting section 242 is configured such that the rising angle β of the slope Ba rising from the upstream toward the throat where the ink flow path cross-sectional area is minimized and the rising angle α of the slope A rising from the downstream toward the throat. , The following relational expression:
It is set so that 0 <β <α ;.

According to this embodiment, the upstream slope Ba is used.
Is inclined downstream toward the throat, so that this slope Ba
Bubbles are less likely to adhere to the surface. That is, the ink flow path 220
By not having a wall which intersects perpendicularly with the flow direction of the ink inside, the adhesion of bubbles is prevented.

[0056]

FIG. 7 is an enlarged sectional view of a resistance applying portion according to another embodiment. The resistance applying section 342 is a combination of the embodiments shown in FIGS. That is, similarly to the embodiment of FIG. 6, the angles β and α rising from the inner wall surface of the ink flow channel 320 toward the throat are 0 <β <α.
And the corners where the ink flow path 320 intersects the slopes Ba and A, and the slopes Ba and A
Are curved surfaces R ₁ , R ₃ and R _2, and the slope Ba facing upstream is subjected to a hydrophilic treatment P.

According to this embodiment, FIGS.
The advantages of each of the embodiments can be combined. Each of the embodiments shown in FIGS.
6 can be used in combination with different resistance applying sections, but it is preferable to use resistance applying sections having the same structure in order to prevent an increase in the number of manufacturing steps.

Further, all the resistance applying portions in each of the ink discharge pumps 24 and 26 may be provided with a structure for preventing the adhesion of bubbles as shown in FIGS. A configuration for preventing bubble adhesion may be provided.

[0059]

According to the first aspect of the present invention, at least one of the upstream side and the downstream side of the cavity provided in the fluid flow path is provided with a resistance applying part having no movable part, and the resistance applying part is provided with a liquid. Since the conductance is adjusted so that the conductance is large in the transport direction and the conductance is small in the reverse direction, the efficiency of the pump can be improved.

In particular, since the hydrophilic treatment is performed on the inner wall surface near the resistance applying portion, air bubbles hardly adhere to the vicinity of the resistance applying portion, and the pump efficiency at the time of discharging the liquid is reduced by the adhesion of the air bubbles. Can be prevented. Further, since the resistance applying portion does not have a movable portion, it can be easily manufactured. For example, the resistance applying portion can be manufactured using a micromachine manufacturing method.

According to the second aspect of the present invention, since the inner wall surface of the resistance applying portion is formed of a curved surface that is smoothly continuous in the liquid transport direction, it is difficult for air bubbles to adhere to the inner wall surface. The same effect as that of the invention is obtained.

According to the third aspect of the present invention, the rising angle β of the slope rising from the upstream side toward the throat of the resistance applying portion.
And the rising angle α of the slope rising from the downstream side toward the throat is set so as to satisfy 0 <β <α, so that there is no wall perpendicular to the ink flow direction, and the bubble Adhesion can be prevented. Therefore, the same effect as that of the first aspect can be obtained.

In order to change the volume of the cavity, the wall of the cavity may be vibrated by a driving unit. However, a part of the wall may be a diaphragm.
The resistance applying section is preferably a divergent nozzle (claim 5).

This liquid transport device can be used for an image recording head such as a printer. In this case, the amount of ink supplied to the ink ejection port is controlled using the liquid transport device. Alternatively, a plurality of inks including the non-image forming liquid and the image forming liquid may be combined to form an ink having a density and / or a color corresponding to the image signal, and the ink may be transferred to the image receiver. If the flow rate is made substantially constant, the transfer of the ink to the image receptor is stabilized. The transfer of the ink may be performed by a continuous coating method,
It may be performed by an ink jet method (claim 7).

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an image recording head.

FIG. 3 is an explanatory diagram of an ink discharge pump.

FIG. 4 is an enlarged cross-sectional view of a resistance applying section.

FIG. 5 is a diagram showing another embodiment of the resistance applying unit.

FIG. 6 is a diagram showing another embodiment of the resistance applying unit.

FIG. 7 is a diagram showing another embodiment of the resistance applying unit.

[Explanation of symbols]

12 Print paper as image receptor 16 Image recording head 20, 120, 220, 320 First ink flow path 22 Second ink flow path 24, 26 Ink ejection pump 28 Ink ejection port 42a, 42b, 44a, 44b, 142, 242, 3
42 resistance application portion 46, 48 cavity 50, 52 diaphragm 54, 56 drive unit A, Ba slope B plane P hydrophilic treatment R _1, R _2, R ₃ curved

Claims (7)

[Claims] 1. A liquid transport apparatus for transporting a liquid in one direction by a change in volume of a cavity provided in a liquid flow path, wherein a movable portion is provided in at least one of an upstream side and a downstream side of the cavity in the liquid flow path. A liquid transport device characterized in that a resistance imparting portion having no resistance is provided so that the direction in which the conductance increases is aligned with the direction of transport of the liquid, and a hydrophilic treatment is performed near the inner wall surface of the resistance imparting portion. 2. A liquid transport apparatus for transporting a liquid in one direction by a change in volume of a cavity provided in a liquid flow path, wherein a movable part is provided in at least one of an upstream side and a downstream side of the cavity part in the liquid flow path. The resistance imparting portion having no resistance is provided so that the direction in which the conductance increases is aligned with the liquid transport direction, and the inner wall surface of the resistance imparting portion is formed of a curved surface that is smoothly continuous in the liquid transport direction. Liquid transport equipment. 3. A liquid transport apparatus for transporting a liquid in one direction by changing the volume of a cavity provided in a liquid flow path, wherein a movable part is provided in at least one of an upstream side and a downstream side of the cavity part in the liquid flow path. The resistance imparting portion having no resistance is provided so that the direction in which the conductance increases is aligned with the liquid transport direction, and the resistance imparting portion rises from the upstream toward the throat where the liquid flow path cross-sectional area is minimized. A liquid transport apparatus, wherein an angle β and a rising angle α of a slope rising from the downstream side toward the throat are set so that 0 <β <α. 4. The liquid transport apparatus according to claim 1, wherein a movable wall driven by a driving unit is provided in the cavity, and a volume of the cavity is changed by moving the movable wall. 5. The liquid transport apparatus according to claim 1, wherein the resistance applying section is a divergent nozzle that is long in the direction of transporting the liquid from the throat and has a short length in the opposite direction. 6. A liquid transport apparatus according to claim 1, which is used in an image recording head for forming an image by transferring ink to an image receptor, and controls an ink ejection amount based on an image signal. . 7. An ink ejected from an ink ejection port by an image recording head is formed of an image non-forming liquid that does not substantially form an image after drying and an image forming liquid that substantially forms an image after drying. 7. The liquid transport apparatus according to claim 6, wherein a discharge amount of each liquid is controlled such that a total flow rate of the non-image forming liquid and the image forming liquid is substantially constant.